Temperature Sensing Unit and Temperature Sensing Method for AI Laptop

The present disclosure relates to a temperature sensor, particularly relates to a temperature sensing unit and a temperature sensing method for an artificial intelligence (AI) laptop.

Apart from the central processing unit (CPU) and the graphics processing unit (GPU), AI laptop further has a neural processing unit (NPU). The overall computing capability needs to be at least 45 TOPS (tera operations per second) or higher to process real-time voice and video signal. With the rapid increased larger inference model during AI training, the need of computing power is greatly increased, and the power consumption is relatively increased by 2-3 times as well, for example, 80-130 Watt for AI laptop. Therefore, the heat management for laptop is becoming important to prevent the chips from overheating and downclocking, which may significantly downgrade the computing power and impact user experience.

The implementation of heat management for laptop is different from that of desktop computer or AI server. Conventional heat management for desktop computer and AI server are water-cooling manner or the mixed manner of water cooling and air cooling. AI lap top can only use fan cooling for heat management due to the height and weight constraints of AI laptop. Traditional gaming laptop adopted the manners of increasing the volume of metal casing and/or continually activating the fan has problem of fan noise which greatly impacts the user experience.

Alternative approach is using the build-in temperature sensor of CPU chip or a thermistor attached to the casing to control the activation and/or speed of the fan. However, those may be close to the heat source, and the severe temperature change may generate annoying fan switching noise. More importantly, AI generation output might have severe delay due to computing power is affected by the over-hated chip. Therefore, a complete solution is needed for applying to AI laptop to provide optimized sustained computing power and to decrease fan noise.

The disclosure adopts non-contact temperature sensor incorporated with calibration and algorithm to provide completely integrated AI laptop heat management to output optimized sustained computing power and decrease fan noise. Furthermore, the disclosure may effectively adjust the apparent temperature at keyboard for better user experience, which is integrated into the heat management system of AI laptop.

One embodiment of the disclosure provides a temperature sensing unit used for an AI laptop, the temperature sensing unit including: a non-contact temperature sensor, sensing an in-machine temperature (Ta) and a target area temperature (Tb); and a processing element, obtaining a ratio of a first thermal resistance (Rac), which is between the target area temperature and an external ambient temperature, and a second thermal resistance (Ri), which is between the in-machine temperature and the target area temperature through a calibration procedure, calculating a predicting external ambient temperature (Tamb) according to, Tamb=Tb−(Ta−Tb)×(Rac/Ri), according to the in-machine temperature, the target area temperature, and the predicting external ambient temperature, to control the activation and speed of a fan, and/or to optimize sustained computing power for AI laptop.

Another embodiment of the disclosure provides a temperature sensing unit used for an AI laptop, the temperature sensing unit including: a non-contact temperature sensor, sensing an in-machine temperature (Ta) and a target area temperature (Tb); and a processing element, obtaining a first ratio of a first thermal resistance (Rac), which is between the target area temperature and an external ambient temperature, and a second thermal resistance (Ri), which is between the in-machine temperature and the target area temperature through a first calibration procedure, calculating a predicting external ambient temperature (Tamb) according to, Tamb=Tb−(Ta−Tb)×(Rac/Ri), obtaining a second ratio of a third thermal resistance (Rc), which is between the target area temperature and an external casing temperature, and the second thermal resistance (Ri), which is between the in-machine temperature and the target area temperature through a second calibration procedure, calculating a predicting external casing temperature (Tskin) according to, Tskin=Tb−(Ta−Tb)×(Rc/Ri), to control the activation and speed of a fan according to the in-machine temperature, the predicting external casing temperature, and the predicting external ambient temperature, and/or to optimize sustained computing power for AI laptop.

The disclosure further provides a temperature sensing method used for an AI laptop, the temperature sensing method including: sensing an in-machine temperature (Ta) and a target area temperature (Tb); obtaining a first ratio of a first thermal resistance (Rac), which is between the target area temperature and an external ambient temperature, and a second thermal resistance (Ri), which is between the in-machine temperature and the target area temperature through a first calibration procedure; calculating a predicting external ambient temperature (Tamb) according to: Tamb=Tb−(Ta−Tb)×(Rac/Ri); according to the in-machine temperature, the target area temperature, and the predicting external ambient temperature, to control the activation and speed of a fan, and/or to optimize sustained computing power for AI laptop.

In summary, the temperature sensing unit used for the AI laptop of the disclosure is using the non-contact temperature sensor to simultaneously obtain three types of temperature characteristics, which are the laptop's internal temperature (in-machine temperature (Ta)), the target area temperature (such as the keyboard temperature), and the ambient temperature (external ambient temperature), to optimize the computing power and reduce fan noise. Specifically, the temperature sensing unit and the temperature sensing method used for the AI laptop of the disclosure may not only measure the surface temperature of the target area, but also estimate the external surface temperature and the ambient temperature of the target area for heat management of the laptop to provide optimized sustained computing power.

As used in the present disclosure, terms such as “first”, “second” are employed to describe various elements, components, regions, layers, and/or parts. These terms should not be construed as limitations on the mentioned elements, components, regions, layers, and/or parts. Instead, they are used merely for distinguishing one element, component, region, layer, or part from another. Unless explicitly indicated in the context, the usage of terms such as “first”, “second” does not imply any specific sequence or order.

is time sequence of the traditional method of controlling air volume and heat dissipation using a temperature sensor built into the chip. The upper curve is the target area temperature (CPU temperature) and the lower curve is variation of the fan speed. The rotational speed of the fan is increasing following increasing of the CPU's temperature, and is decreasing following decreasing of the CPU's temperature with some time delay. Thus, the variation frequency of the rotational speed is frequently changed with respect to the CPU's temperature variation. The fan noise in this manner is the most annoying one that has worst user experience.

is time sequence of the traditional method of controlling air volume and heat dissipation using a thermistor. The thermistor is generally disposed on the main board. The upper curve is the target area temperature (main board temperature) and the lower curve is variation of the fan's air volume. The rotational speed of the fan is increasing following increasing of the temperature sensed by the thermistor, and is decreasing following decreasing of the temperature sensed by the thermistor. Thus, the variation frequency of the rotational speed is frequently changed with respect to the main board's temperature variation. The thermistor is a contact type temperature sensor. Although the variation range of the temperature information from the thermistor is smaller than that of the temperature sensor in the CPU, but the fundamental problem is not solved. Thus, the fan noise in this manner is slightly improved, but the user experience is still not good enough.

is time sequence of proposed method of controlling air volume and heat dissipation using a non-contact thermopile sensor. The target temperature measured by the infrared temperature sensor is the element casing temperature of the laptop, that is far from the heat source, and the influence of thermal shock from the CPU may be omitted. The temperature being measured is equivalent to the average temperature of the dramatically changed CPU temperature passing through the low pass filter. Thus, the temperature is more stable to be an ideal temperature for feedback temperature control. The fan noise in this manner is the lowest, and the user experience is the best.

In the usage of AI laptop, the key concern is to provide sustained computing power. Therefore, the signals such as the target area temperature, the in-machine temperature, and the ambient temperature (external ambient temperature) may be used for temperature controlling. Particularly, the ambient temperature may influence the sustained computing power to be provided.

The temperature sensing unit of the disclosure includes the non-contact temperature sensor and the processing element. The non-contact temperature sensor is used to measure the target area temperature (Tb) (such as the temperature of the casing or the monitoring point), and the build-in thermistor of the thermopile sensor or the build-in temperature sensor of the processing element may provide the in-machine temperature signal (Ta). The predicting external ambient temperature (Tamb) may be calculated through the calibrated computing parameter and the measured temperature signals (Ta, Tb).

Examples of non-contact temperature sensor including thermopile sensor, thermal-diode sensor or thermistor sensor sitting on membrane with cavity that can detect infrared thermal radiation of external objects.

is the schematic diagram of the application of the disclosure. The non-contact temperature sensoris disposed adjacent to the laptop CPU chip. The non-contact temperature sensoris used for monitoring the target area temperature Tb. In the embodiment, the target area temperature Tb is the temperature of the laptop keyboard. The laptop substrateis used for carrying the electronic components. The build-in thermistor of the non-contact temperature sensoror the build-in temperature sensor of the processing elementmay measure the in-machine temperature Ta. The external casing temperature of the laptop keyboardat the target area is Tskin, and the external ambient temperature is Tamb.andshows the model of the temperature at each point and the thermal resistance under the heat flow H. The thermal resistance (first thermal resistance) Ra is between the external casing temperature Tskin of the target area and the ambient temperature Tamb. The thermal resistance (second thermal resistance) Ri is between the in-machine temperature Ta, which is sensed by the non-contact temperature sensoror processing element, and the target area temperature Tb. Similarly, the thermal resistance (third thermal resistance) Rc is between the target area temperature Tb and the surface temperature Tskin at the target area. For facilitating analyzing, Ra and Rc may be simplified as Rac as shown into acquire the ambient temperature Tamb based on the target area temperature Tb.

Under thermal equilibrium, the ambient temperature Tamb may be obtained by the in-machine temperature Ta, the target area temperature Tb, and the first ratio Rac/Ri as shown in equation (1).

The first ratio Rac/Ri may be obtained through the calibration procedure (first calibration procedure). When in use, the predicting ambient temperature (predicting external ambient temperature) Tamb may be obtained according to equation (1) by the measured in-machine temperature Ta and the measured target area temperature Tb. The predicting ambient temperature Tamb and the target area temperature Tb are used to control the activation of the fan and appropriately adjust the air volume to make the laptop chip work under thermal safe zone to provide optimized sustained computing power.

The laptop's computing power is related to the fan's heat dissipation capability as shown below;

The equation of the fan's heat dissipation amount is, Q=0.05 P/ΔTc.

Q is the air volume needed for cooling (unit: Cubic Meter per Minute, CMM). P is the thermal design power (unit: Watts, W). ΔTc is the temperature difference between the chip's working temperature and the external ambient temperature (unit: ° C.).

Presumably, the highest temperature in summer is 35° C. (designed temperature), CPU's allowable case working temperature is 80° C., and the fan's designed air volume is 0.1667 CMM.

The embodiment describes the influence from the ambient temperature to the sustained computing power provided by the laptop in the application of the AI laptop. Therefore, the fan control is related to the chip's optimized computing power, the in-machine temperature Ta, the target area temperature Tb, and the ambient temperature Tamb. The disclosure provides a solution for continuously optimizing the computing power. The disclosure is also used for more precisely predicting the surface temperature of specific area.

Referring to, the embodiment uses the in-machine temperature Ta and the target area temperature Tb to calculate the predicting external ambient temperature Tamb based on the equation (1). The thermal resistance ratio Rac/Ri is used, and that may be obtained through the calibration procedure as described below.

(it may be obtained by measuring outside air of the laptop though the other temperature sensor);

from the thermopile sensors installed inside;

It should be noted that the star (*) sign in variables indicates the measured value during calibration procedure. The thermal resistance ratio Rac/Ri may be stored in the non-volatile memory of the non-contact temperature sensor. In the practical application, the predicting ambient temperature Tamb is obtained by equation (2) based on the measured in-machine temperature Ta, the measured target area temperature Tb, and the thermal resistance ratio Rac/Ri from the calibration procedure. Then the predicting ambient temperature Tamb, the target area temperature Tb, and the in-machine temperature Ta may be used for controlling the fan speed to optimize sustained computing power.

is the curve graph of predicting external ambient temperature under varied heat source during experiment. From Top to bottom, four curves are the in-machine temperature Ta, the target area temperature Tb, the realistic external ambient temperature {circumflex over (T)}amb, and the predicting external ambient temperature Tamb, respectively. As shown in, during the stage that the in-machine temperature Ta is beginning to increased, the predicting external ambient temperature Tamb has an error of about 2° C. comparing to the realistic external ambient temperature {circumflex over (T)}amb. Afterward, the predicting external ambient temperature Tamb is substantially the same as the realistic external ambient temperature {circumflex over (T)}amb. The estimation error of ambient temperature is larger when the heat source is increasing. Even at the transition stage, the estimation error to the ambient temperature is within 1° C., which proves the effectiveness of the disclosure in predicting the external ambient temperature.

Another embodiment of the disclosure is used for calculating the predicting external casing temperature Tskin at the target area. The thermopile sensor is used to measure the target area temperature Tb, which is the inside surface temperature at the target area. If the surface casing temperature needs to be monitored is not right above the thermopile sensor, for example, at the area laterally distanced×centimeter from the thermopile sensor underneath, the embodiment is still applicable which is shown as equation (3).

Under thermal equilibrium case, the predicting external casing temperature Tskin may be obtained by the in-machine temperature Ta, the target area temperature Tb, and the second ratio Rc/Ri. The second ratio Rc/Ri may be obtained through the second calibration procedure as shown below;

(it may be obtained by measuring the surface temperature of the laptop's external casing though another temperature sensor);

The second ratio Rc/Ri may be stored in the non-volatile memory of the non-contact thermopile sensor. In the practical application, the predicting external casing temperature Tskin is obtained by equation (4) based on the measured in-machine temperature Ta, the measured target area temperature Tb, and the second ratio Rc/Ri obtained from the calibration procedure.

In some embodiments, the non-contact temperature sensor may use a single thermopile sensing element. The single thermopile sensing element may sense the target area temperature Tb, and the build-in thermistor of the single thermopile sensing element may provide the in-machine temperature Ta.

In some other embodiments, the non-contact temperature sensor may use a dual thermopile sensing element (two thermopile sensing elements) for compensating package casing effect and for providing anti thermal shock capability. That is because the internal temperature of the laptop may change abruptly and the normal single thermopile sensor may not be able to provide accurate temperature measurement under the severe heat change condition. One of the dual thermopile sensing elements is used as an active unit for measuring the temperature of the target object, and the other one of the dual thermopile sensing elements is used as a compensation unit (dummy unit) for compensating the influence from the package structure. As a result, the disclosure may precisely measure the temperature under the ambient temperature in severely changing situation. In this condition, the in-machine temperature Ta signal may be obtained by the build-in thermistor of the dual thermopile sensing element or the build-in temperature sensor of the processing element.

Referring toand, in some embodiments, the dual thermopile sensing elementmay, for example, include an infrared sensing chip, a silicon cover, a microcontroller chip, a package substrate, and a sealing encapsulation.

The infrared sensing chipincludes a first substrate, a first thermopile sensing element, a second thermopile sensing element, and a front-end signal processing unit. In some embodiments, the first substratehas a wire-bonding padand two membrane structures (or floating plate structures),formed by a front-side wet etching. The wire-bonding padand the membrane structures,are disposed correspondingly. In some embodiments, the wire-bonding padis disposed on the edge of the first substratefor wire bonding to the microcontroller chip, and the membrane structures,are disposed away from the wire-bonding padand disposed corresponding to the silicon cover.

In some embodiments, the first substratefurther includes two concave portions,corresponding to the membrane structures,respectively. In other words, the membrane structureis located above the concave portion, and the membrane structureis located above the concave portion.

The first thermopile sensing elementis disposed on the membrane structurecorresponding to the concave portion. A hot junction of the first thermopile sensing elementis located on the membrane structure, and a cold junction of the first thermopile sensing elementis located on the periphery of the concave portion. The first thermopile sensing elementmay sense a temperature of the target area to be sensed and generate the target area temperature Tb.

In some embodiments, the second thermopile sensing elementis disposed on the membrane structurecorresponding to the concave portion. The second thermopile sensing elementis disposed adjacent to the first thermopile sensing element. A hot junction of the second thermopile sensing elementis located on the membrane structure, and a cold junction of the second thermopile sensing elementis located on the periphery of the concave portion. The window portion of the second thermopile sensing elementis covered by metal, thereby the second thermopile sensing elementmay merely sense the thermal radiation of the silicon coverto generate a compensation temperature signal.

In some embodiments, the front-end signal processing unitis disposed on the first substrateand electrically connected with the first thermopile sensing elementand the second thermopile sensing element.